ps2cho, I'd never take a car to Pep Boys for any work. Too bad you didn't return to Pep Boys as soon as you noticed the noise because it's likely their tech did something to cause the noise. Since you have waited a week or more it will be more difficult to have them accept responsibility for any damage/repair work. In the future you're better off having a MB dealer or tech work on your MB vehicle. I buy tires from Tire Rack and have our local dealer install them because only a MB dealer has the MB 2-piece balance weights.

__________________
Fred Hoelzle